title: Thymidine phosphorylase in cancer cells stimulates human endothelial cell migration and invasion by the secretion of angiogenic factors.
abstract: BACKGROUND
  Thymidine phosphorylase (TP) is often overexpressed in tumours and has a role in tumour aggressiveness and angiogenesis. Here, we determined whether TP increased tumour invasion and whether TP-expressing cancer cells stimulated angiogenesis.
  
  
  METHODS
  Angiogenesis was studied by exposing endothelial cells (HUVECs) to conditioned medium (CM) derived from cancer cells with high (Colo320TP1=CT-CM, RT112/TP=RT-CM) and no TP expression after which migration (wound-healing-assay) and invasion (transwell-assay) were determined. The involvement of several angiogenic factors were examined by RT-PCR, ELISA and blocking antibodies.
  
  
  RESULTS
  Tumour invasion was not dependent on intrinsic TP expression. The CT-CM and RT-CM stimulated HUVEC-migration and invasion by about 15 and 40%, respectively. Inhibition by 10 μM TPI and 100 μM L-dR, blocked migration and reduced the invasion by 50-70%. Thymidine phosphorylase activity in HUVECs was increased by CT-CM. Reverse transcription-polymerase chain reaction revealed a higher mRNA expression of bFGF (Colo320TP1), IL-8 (RT112/TP) and TNF-α, but not VEGF. Blocking antibodies targeting these factors decreased the migration and invasion that was induced by the CT-CM and RT-CM, except for IL-8 in CT-CM and bFGF in RT-CM.
  
  
  CONCLUSIONS
  In our cell line panels, TP did not increase the tumour invasion, but stimulated the migration and invasion of HUVECs by two different mechanisms. Hence, TP targeting seems to provide a potential additional strategy in the field of anti-angiogenic therapy.
authors.affiliation: Department of Medical Oncology, VU University Medical Center, PO Box 7057, 1007 MB, Amsterdam, The Netherlands.
authors.forename: I V
authors.initials: IV
authors.lastname: Bijnsdorp
authors.forename: F
authors.initials: F
authors.lastname: Capriotti
authors.forename: F A E
authors.initials: FA
authors.lastname: Kruyt
authors.forename: N
authors.initials: N
authors.lastname: Losekoot
authors.forename: M
authors.initials: M
authors.lastname: Fukushima
authors.forename: A W
authors.initials: AW
authors.lastname: Griffioen
authors.forename: V L
authors.initials: VL
authors.lastname: Thijssen
authors.forename: G J
authors.initials: GJ
authors.lastname: Peters
mesh_terms: D043925:Angiogenesis Inducing Agents / Q000378:metabolism*; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D042783:Endothelial Cells / Q000201:enzymology / Q000502:physiology*; D016222:Fibroblast Growth Factor 2 / Q000235:genetics; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism; D006801:Humans; D016209:Interleukin-8 / Q000235:genetics; D009361:Neoplasm Invasiveness; D009369:Neoplasms / Q000201:enzymology* / Q000378:metabolism; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D013939:Thymidine Phosphorylase / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D043925:Angiogenesis Inducing Agents; D016209:Interleukin-8; D014409:Tumor Necrosis Factor-alpha; D042461:Vascular Endothelial Growth Factor A; D016222:Fibroblast Growth Factor 2; D013939:Thymidine Phosphorylase; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human; D038762:Ribosomal Protein S6 Kinases, 70-kDa